Robotics research into multi-robot systems so far has concentrated on implementing intelligent swarm behavior and contact-less human interaction. Studies of haptic or physical human-robot ...interaction, by contrast, have primarily focused on the assistance offered by a single robot. Consequently, our understanding of the physical interaction and the implicit communication through contact forces between a human and a team of multiple collaborative robots is limited. We here introduce the term Physical Human Multi-Robot Collaboration (PHMRC) to describe this more complex situation, which we consider highly relevant in future service robotics. The scenario discussed in this article covers multiple manipulators in close proximity and coupled through physical contacts. We represent this set of robots as fingers of an up-scaled agile robot hand. This perspective enables us to employ model-based grasping theory to deal with multi-contact situations. Our torque-control approach integrates dexterous multi-manipulator grasping skills, optimization of contact forces, compensation of object dynamics, and advanced impedance regulation into a coherent compliant control scheme. For this to achieve, we contribute fundamental theoretical improvements. Finally, experiments with up to four collaborative KUKA LWR IV+ manipulators performed both in simulation and real world validate the model-based control approach. As a side effect, we notice that our multi-manipulator control framework applies identically to multi-legged systems, and we execute it also on the quadruped ANYmal subject to non-coplanar contacts and human interaction.
Assistive devices like exoskeletons undergo extensive testing not least because of their close interaction with humans. Conducting user studies is a time-consuming process that demands expert ...knowledge, and it is accompanied by challenges such as low repeatability and a potential lack of comparability between studies. Obtaining objective feedback on the exoskeleton’s performance is crucial for developers and manufacturers to iteratively improve the design and development process. This paper contributes to the concept of using robots for objective exoskeleton testing by presenting various approaches to a robotic-based testing platform for upper-body exoskeletons. We outline the necessary requirements for realistically simulating use cases and evaluate different approaches using standard manipulators as robotic motion generators. Three approaches are investigated: (i) Exploiting the anthropomorphic structure of the robotic arm and directly placing it into the exoskeleton. (ii) Utilizing a customized, direct attachment between the robot and exoskeleton. (iii) Attaching a human arm dummy to the robot end effector to simulate a more realistic interface with the exoskeleton. Subsequently, we discuss and compare the results against the aforementioned requirements of a systematic testing platform. Our conclusion emphasizes that achieving objective and realistic testing necessitates highly specialized hardware, algorithms, and further research to address challenging requirements.
Integrated environmental analysis using life cycle assessment for different fuel blends used in a single-cylinder diesel engine was performed to select the most eco-friendly fuel blend. More ...specifically, the inventory data in support of the integrated environmental analysis of water-emulsified 5% biodiesel/diesel blends (B5) containing different levels of carbon nanoparticles (i.e., 38, 75, and 150 µM) as a novel fuel nanoadditives at a fixed engine speed of 1000 rpm and four different engine loads (i.e., 25, 50, 75, and 100%) are presented. Neat diesel, B5, and B5 containing water (3 wt.%) were used as controls. Raw data related to the production and combustion of fuel blends were experimentally collected. Industrial (i.e., experiments at large scale) and laboratory (i.e., experiments at small scale) data were used for fuel blends production while experimental data obtained by engine tests were used for the combustion stage. Then raw data were processed with the IMPACT 2002+ methods by using the SimaPro software and EcoInvent database and were then converted into environmental impacts. Accordingly, six supplementary files including the inventory data on integrated environmental analysis of the different fuel blends are presented (Supplementary Files 1–6). The data could be applied for integrated environmental analysis in order to avoid subjective weighting of combustion parameters for selecting the most eco-friendly fuel blend for use in diesel engines. More specifically, by developing a single score indicator obtained through conducting integrated combustion analysis, comparison of various fuel blends is largely facilitated.
Due to the fast fossil fuel depletion and at the same time global warming phenomenon anticipated for the next coming years, the necessity of developing alternative fuels e.g. biofuels (i.e. ...bioethanol, biodiesel, biogas and etc.) has turned into an important concern. Recently, the application of the bio-solvency properties of biodiesel for recycling waste polymers has been highlighted. However, the impact of polymer dissolution on cold flow characteristics of biodiesel was never investigated. The present study was set to explore the impact of different solvents in stabilizing biodiesel-polymer solution. Among them, acetone was proved to be the best fuel stabilizer. Subsequently, cold flow characteristic i.e. cloud point, of the biodiesel-polymer-acetone fuel was found to have improved (decreased) due to the inclusion of acetone. Finally, flash point analysis of the fuel blends containing acetone was done to ensured high safety of the fuel blend by dramatically increasing the flash point values of biodiesel-polymer fuel blends.
In this study, a novel low power, high frequency piezoelectric-based ultrasonic reactor was developed and evaluated for intensifying the transesterification process. The reactor was equipped with an ...automatic temperature control system, a heating element, a precise temperature sensor, and a piezoelectric-based ultrasonic module. The conversion efficiency and specific energy consumption of the reactor were examined under different operational conditions, i.e., reactor temperature (40‒60 °C), ultrasonication time (6‒10 min), and alcohol/oil molar ratio (4:1‒8:1). Transesterification of waste cooking oil (WCO) was performed in the presence of a base-catalyst (potassium hydroxide) using methanol. According to the obtained results, alcohol/oil molar ratio of 6:1, ultrasonication time of 10 min, and reactor temperature of 60 °C were found as the best operational conditions. Under these conditions, the reactor converted WCO to biodiesel with a conversion efficiency of 97.12%, meeting the ASTM standard satisfactorily, while the lowest specific energy consumption of 378 kJ/kg was also recorded. It should be noted that the highest conversion efficiency of 99.3 %, achieved at reactor temperature of 60 °C, ultrasonication time of 10 min, and alcohol/oil molar ratio of 8:1, was not favorable as the associated specific energy consumption was higher at 395 kJ/kg. Overall, the low power, high frequency piezoelectric-based ultrasonic module could be regarded as an efficient and reliable technology for intensifying the transesterification process in terms of energy consumption, conversion efficiency, and processing time, in comparison with high power, low frequency ultrasonic system reported previously. Finally, this technology could also be considered for designing, developing, and retrofitting chemical reactors being employed for non-biofuel applications as well.
•Exergoeconomic and exergoenvironmental analyses were applied for a DI diesel engine.•Increasing engine load remarkably decreased the unit cost of shaft work exergy.•Increasing engine speed increased ...the unit environmental impact of work exergy.•The applied approaches could not detect any spectacular difference among the fuels.
In the present study, a DI diesel engine operating on various diesel/biodiesel blends containing different amounts of polymer waste was thermodynamically scrutinized using two exergy-based methods, i.e., exergoeconomic and exergoenvironmental analyses for the first time. Exergoeconomic and exergoenvironmental parameters were calculated for five fuel blends utilized throughout this study at different engine loads and speeds. These approaches were used to make decisions on fuel composition and engine operational conditions by taking into account the financial and environmental issues. The results showed that the exergoeconomic and exergoenvironmental parameters varied profoundly with engine load and speed. In general, increasing engine load remarkably decreased the unit cost and the unit environmental impact of the shaft work exergy, while enhancing engine speed acted oppositely. More specifically, the lowest unit cost and unit environmental impact of full load work exergy were found to be 36.08USD/MJ and 32.03mPts/GJ for neat diesel and B5 containing 75gEPS/L biodiesel, respectively, both at engine speed of 1600min−1. Moreover, the exergoeconomic and exergoenvironmental factors of the diesel engine were very poor due to the higher thermodynamic losses occurring during the combustion process. Although the maximum exergetic efficiency of the diesel engine was obtained for B5 including 50gEPS/L biodiesel, the exergoeconomic and exergoenvironmental analyses could not detect any spectacular differences among the fuel blends applied. Overall, using biodiesel in neat or blended form appeared to be less attractive strategy from the exergoeconomic and exergoenvironmental perspectives considering the current biodiesel prices and production technologies.
•A biofueled tractor diesel engine was exergetically, economically, and environmentally studied.•Biodiesel could improve the exergetic, economic, and environmental indicators of the system.•There was ...no clear pattern of the effects of bioethanol on the investigated indicators.•Biofuel blends were exergetically, economically, and environmentally superior to diesel.•The best results were found for the blend containing 10 vol% biodiesel and 4 vol% bioethanol.
This study aimed to analyze a heavy-duty tractor diesel engine operating on diesel-biodies-bioethanol blends using exergetic, economic, and environmental life cycle assessment analyses. Diesel was mixed with biodiesel and bioethanol with volumetric ratios of 5–15% and 2–6%, respectively. Nine diesel–biodiesel-bioethanol blends and one baseline fuel were tested at different PTO shaft speeds ranging from 800 to 1000 rpm under full load operating conditions. Various exergetic, economic, and environmental indicators were computed to facilitate decision-making on fuel composition and PTO shaft speed. In general, increasing biodiesel concentration in the fuel blend could improve the exergetic, economic, and environmental indicators of the system. However, there was no clear pattern of the effects of bioethanol on the investigated indicators. Interestingly, most of the prepared fuel blends were exergetically, economically, and environmentally superior to diesel. The lowest weighted environmental impact (52.1 mPts/GJ) and PTO shaft power generation cost (0.18 USD/kWh) were found for the fuel blend containing 10 vol% biodiesel and 4 vol% bioethanol at the PTO shaft speed of 1000 rpm. This fuel blend also showed the highest resource utilization efficiency (29.3%) and environmental sustainability (26.1%) at the PTO shaft speed of 1000 rpm. The weighted environmental impact and PTO shaft power generation cost of the selected fuel blend were 44.3% and 46.2% lower than those of diesel, respectively. The resource utilization efficiency and environmental sustainability of the selected fuel blend were 97.3% and 99.8% higher than those of diesel, respectively. Overall, substituting a portion of diesel with biodiesel and bioethanol was proved to be an attractive strategy from the exergetic, economic, and environmental perspectives. The results obtained can be valuable in practical applications to enhance the sustainability and viability of power production in agricultural activities. The applied exergetic, economic, and environmental methodologies appear to be reliable and comprehensive tools for assessing the whole-life sustainability and viability of mineral-biofuel blends.
•Effects of carbon nanoparticles on the combustion of a diesel engine were studied.•Carbon nanoparticles addition into fuels markedly lowered nitrogen oxides emissions.•Carbon nanoparticles increased ...unburned hydrocarbon emissions at full load conditions.•Carbon nanoparticles promoted carbon monoxide formation under full load operation.•Power generation cost could be discounted by adding carbon nanoparticles into fuels.
Biodiesel utilization is associated with reduced calorific value and increased nitrogen oxides emissions. Hence, various strategies are implemented to address these challenges such as water addition into diesel/biodiesel fuel blends. In line with that, this study was undertaken to explore the effect of water (3 wt.%) and aqueous carbon nanoparticles (38, 75, and 150 µM), as a novel fuel nanoadditive, on combustion and exhaust emissions of a diesel engine at a fixed engine speed of 1000 rev/min under four different engine loads ranging from 25% to 100% of full load conditions. Overall, the engine performance characteristics were improved by incorporating the aqueous carbon nanoparticles. In particular, the incorporation of carbon nanoparticles into water-emulsified biodiesel/diesel blends generally enhanced brake power and thermal efficiency while lowering specific fuel consumption. The most appealing performance features were observed for the emulsified fuel blend containing 38 µM carbon nanoparticles which increased brake power and brake thermal efficiency by 1.07 kW and 11.58% at full load operation, respectively, while it led to decreased brake specific fuel consumption by about 107.3 g/kWh. The addition of carbon nanoparticles to the water-emulsified fuel blends adversely affected unburned hydrocarbons and carbon monoxide emissions at full load conditions owing to an increase in carbon content of the fuel blends but it lowered nitrogen oxides emissions. The addition of water deteriorated the economic features of the fuel blend (i.e., the cost per kWh of power generated). However, carbon nanoparticles addition into the water-emulsified fuel blend partially neutralized the adverse economic effects of water due to its positive impacts on thermal efficiency. Overall, water-emulsified diesel/biodiesel containing 38 µM carbon nanoparticles could be regarded as the most promising emulsion fuel in terms of engine performance characteristics, nitrogen oxides emissions, as well as fuel economy.
•Exergy analysis of a single cylinder DI diesel engine at various engine loads.•Water/diesel/biodiesel emulsions with cerium oxide nanoparticle as fuel blends.•Engine load and fuel type profoundly ...affected sustainability indices of the engine.•B5 blend with 3w/w% water and 90ppm nanoparticles showed the best performance.
This survey was aimed at determining exergy-based sustainability parameters of a single cylinder DI diesel engine in response to various fuel blends and engine loads at a fixed engine speed of 1000rpm. Engine tests were conducted at four engine loads (25%–100%) using a 95% diesel+5%biodiesel blend (B5) emulsified with water (3, 5, and 7w/w%). All the prepared emulsions were stabilized with a 2:1 combination of Span 80 and Tween 80 (overall 7.5w/w% surfactant). Two levels of cerium oxide nanoparticle concentrations (0 and 90ppm) were also applied. The results showed that engine load and fuel type profoundly affected the exergy-based sustainability indices of the engine. Generally, increasing engine load steadily decreased exergy efficiency, while normalized exergy destruction declined by up to 75% under full load condition. Among the fuel blends prepared, the B5 blend containing 3w/w% water and 90ppm cerium oxide nanoparticles (B5W3m) showed the best exergy-based sustainability parameters at all the studied engine loads as its respective performance approached that of the basal petro-diesel. More specifically, among the fuel blends prepared the highest exergetic efficiency and the lowest normalized exergy destruction at full load condition were achieved using the selected fuel blend at 28.26% and 1.52, respectively. These values stood at 28.36% and 1.69 for neat diesel, respectively. However, the selected emulsified fuel blend represented a remarkably better environmental performance compared with diesel fuel. In conclusion, the B5W3m fuel blend might be effectively applied as substitute to mineral diesel fuel without any change in the existing engine structure.
The present study was set to explore the effect of a novel soluble hybrid nanocatalyst in diesel/biodiesel fuel blends on exergetic performance parameters of a DI diesel engine. Experiments were ...carried out using two types of diesel/biodiesel blends (i.e., B5 and B20) at four concentrations (0, 30, 60 and 90 ppm) of the hybrid nanocatalyst, i.e., cerium oxide immobilized on amide-functionalized multiwall carbon nanotubes (MWCNT). Furthermore, the exergy analysis was performed at five different loads and two engine speeds. The results obtained revealed that the exergetic parameters were profoundly influenced by engine speed and load. In general, increasing engine speed and load increased the magnitude of the destructed exergy. Moreover, the exergy efficiency increased by increasing engine load, while it decreased by elevating engine speed. However, the applied fuel blends had approximately similar exergetic efficiency and sustainability index. Interestingly, a remarkable reduction in emissions was obtained by incorporating the soluble catalyst nanoparticles to the diesel/biodiesel blends. Thus, it could be concluded that the diesel/biodiesel blends containing amide-functionalized MWCNTs-CeO2 catalyst might substitute the use of pure diesel fuel without any unfavorable change in the exergetic performance parameters of the DI engines.
•Exergetic assessment of a DI engine fueled with B5 and B20 containing hybrid nano-catalyst.•Significant effect of engine speed and load on exergetic parameters of the engine.•Non-important difference in the exergetic performance parameters of the engine running with various fuel blends.•Potential application of the developed nanocatalyst for reducing the emissions without any irreversibility increment.
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